1. Field of the Invention
The present invention relates generally to the field of biochemical laboratory instrumentation for different applications of microtitration plates and corresponding sample supports. More particularly the invention relates to an improved and more complete combination of the instrumental features of fluorometers, photometers and luminometers.
In this patent application the term "photoluminescence" is used to mean "any optical photon emission generated by incident optical radiation". The term "fluorescence" has had the same meaning in older writings but now "fluorescence" should refer purely to molecular processes.
2. Description of Prior Art
The typical instruments in analytical chemical research laboratories are the different spectroscopic instruments. Many of them utilize optical region of the electromagnetic spectrum. The two common type of the instruments are the spectrophotometers and the spectrofluorometers. These instruments comprise usually one or two wavelength dispersion devices, such as monochromators. The dispersion devices make them capable of performing photometric and fluorometric measurements throughout the optical spectrum.
The routine work and also the research work in analytical biochemical laboratories and in clinical laboratories are often based on different tags or labels coupled on macromolecules under inspection. The typical labels used are different radioactive isotopes, enzymes, different fluorescent molecules and e.g. fluorescent chelates of rare earth metals.
The detection of enzyme labels can be performed by utilizing their natural biochemical function, i.e. to alter the physical properties of molecules. In enzyme immunoassays colorless substances are catalyzed by enzymes to colorful substances or non-fluorescent substances to fluorescent substances. That is why the different instrumental methods of measurements are needed.
Biochemical and clinical laboratories have gamma- and betacounters for radioisotopes, filter photometers for colorimetric immunoassays and for clinical chemistry determinations, filter fluorometers for fluorescent immunoassays, luminometers for chemical luminescence, time-resolved fluorometers, etc.
But there are not many instruments on the market which are capable of using more than one measurement technology in the same instrument. Technically all fluorometers are capable of measuring glow-type chemical luminescence but this is not utilized in many instruments.
One of the instruments is a spectrofluorometer by Perkin Elmer Corporation, which spectrofluorometer due to its flash-type excitation lamp and analogue detection method is capable of measuring fluorescence, phosphorescence and luminescence from cuvettes. The said company is supplying a fibre optics option for microtitration plates. However, a spectrofluorometer is intrinsically a far less sensitive instrument than a filter fluorometer and a fibre optics system decreases even more the sensitivity of the instrument.
On the market there is also an instrument named "Fluostar" originally made by BMG LabTechnologies GmbH, Offenburg, Germany. This instrument is capable of measuring conventional fluorescence and time-resolved photoluminescence. It has light guides both in the excitation side and in the emission side and its detection technology is based on the gated analogue often called "boxcar" detection. The use of light guides technology in the emission side and the analogue detection are both the limiting sensitivity of the instrument.
On the market there is also a device including combined photometer and luminometer named "Anthos Lucy" by Labtech International, Uckfield, Great Britain. Also there is coming to the market a combined fluorometer and photometer from Molecular Dynamics, Inc., California. The further perfomance of the devices are not known.
As far as the inventor knows there are no instrumentation for microtitration plates or alike sample supports capable of measuring the following four technologies. The technologies are photoluminescence, absorption, chemical luminescence and time-resolved photoluminescence.
The applicant Wallac company has manufactured time-resolved fluorometers since 1983. The first model of the instrument, called Arcus 1230, was able to count only tubes in racks or strips of microtitration plates in racks. The fluorescent solution was excited through the wall of a tube or a well of the strips. Emission was collected from bottom. The second model Wallac time-resolved fluorometer 1232 was introduced in 1988 and it was able to measure the whole microtitration plate. The excitation optics is situated on the upper side of the plate and it comprises three quartz lenses and filters. The emission optics is below of the sample and it comprises ultra-violet filter and three plastics lenses. Few years later there was introduced a model called 1234 with two additional interference filters in the emission side. However, all these instruments are using only time-resolved photoluminescence measurement technology.